> On Jun 10, 2016, at 01:32 , valdis.kletni...@vt.edu wrote:
>
> On Fri, 10 Jun 2016 07:19:22 +0100, "t...@pelican.org" said:
>
>> All the business systems that sit around it? Not so much. $DAYJOB has
>> plenty of code, database structures etc that are built around "an IP address
>> is
>> no more than 15 characters long and matches
>> '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'". To fix that, you need
>> development time - typically expensive analyst time to work out *what* you
>> need
>> to change, not just code-grinder make-the-field-bigger time. IT departments
>> seem reluctant to provide that resource, unless you've got people at the very
>> top of the business bought into the fact that you *need* to do IPv6.
That was a pretty dumb way to store IPv4 addresses, frankly.
First, 593.812.904.601 matches your regular expression, and isn’t an IP address.
If you were smart (IMHO), you stored IPv4 addresses as 32-bit integers.
First, update the software in question to understand IPv4 mapped addresses for
parsing/displaying (IPv4->::ffff:i.p.v.4 for parsing and reverse the process
for display) and then modify the database schema.
With most databases and other software, converting a 32-bit integer field into
a 128 bit integer field isn’t particularly hard.
Once you’ve done that, make a quick single pass through the database adding
281,470.681.743.360 to all integers < 4,294,967,296.
(That should replace the equivalent of 0:0:0:0:0:0:ip:v4 with the equivalent of
0:0:0:0:0:ffff:ip:v4)
There are a number of reasons for converting all IP addresses to integers prior
to processing in software.
1. Easier and more consistent sorting.
2. Consistent and easier comparisons for equality or ranges
In iPv4, this was useful. In IPv6, it’s essential.
e.g.
IPv4: 90.90 == 90.0.0.90
IPv4: 33280.33288 == 130.0.130.8
IPv6: All of the following are equal
2001:db8::3
2001:0db8::0003
2001:0db8:0:0:0:0:0:3
2001:db8:0::3
etc.
Also:
2620::930:0:0:0:200:2
2620:0:930::200:2
etc.
3. Easier to deal with future changes (such as expanding from 32-bit IPv4
numbers to 128-bit IPv6 numbers)
4. Representation can be left to the user interface where it belongs
instead of embedded throughout the application.
The network stack only deals with integers, why not keep them as
integers everywhere else as well. The other
expressions are just for human readability. Treat them like any other
Locale based UI issue.
Yes, you need to get the people at the top bought into the idea that IPv6 must
be deployed, but these days, that really shouldn’t be all that hard to do with
competent management and a reasonable networking department.
Owen
